EvervaultConfigurator

Configures Evervault once and lets concurrent callers await that same work, mirroring iOS's EvervaultConfigurator actor.

FrameNetworking.configureEvervault fetches credentials asynchronously before applying them, so a caller that kicks off configuration and encrypts on the next line can encrypt before the client exists. Awaiting ensureConfigured closes that window, and concurrent callers join the same in-flight fetch rather than firing duplicate requests.